Loans, Lending Commitments and Allowance for Credit Losses - Employee Loans (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
Sep. 30, 2019	Dec. 31, 2018
Employee Loans
Balance	$ 2,990	$ 3,415
Allowance for loan losses	(61)	(63)
Balance, net	$ 2,929	$ 3,352
Repayment term range, in years	4 years 8 months 12 days	4 years 3 months 18 days

For an unclassified balance sheet, amounts due from an Entity employee, not to include stockholders or officers.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant